Numerical Investigation of the Effect of Changing the Thickness of Airfoils used in Wind Turbines on the Lift to Drag Ratio

In this paper, the effect of changing the thickness of the airfoils on the lift and drag coefficients and lift to drag ratio for three types of airfoils is presented. The study was done by making a 2D simulation by using the commercial software ANSYS FLUENT 2019R1. The airfoils that were selected for the simulation were the NREL S830, SG6043, and SD7062. In order to study the effect of changing the thickness of airfoils on the aerodynamic characteristics, the thickness of NREL S830, SG6043, and SD7062 airfoils was increased and decreased by 20%. The method used to increase and decrease the thickness was done by modifying the coordinates of the upper and lower curves of the baseline airfoils in the y-direction. The simulation was done using the Spalart Allmaras turbulence model for low wind speed (5m/s) and a wide range of attack angles (from 0 to 15 degrees). The aerodynamic characteristics, which are the lift and drag coefficients, lift to drag ratio, and the optimum angle of attack, are presented in this study. It was concluded that reducing the thickness to 20% leads to a remarkable increase in the lift to drag ratio while increasing the thickness leads to a decrease in the lift to drag ratio. It was also concluded that reducing thickness will not always lead to maximizing the lift coefficient but will always reduce the drag coefficient. It was also found that for wind turbines operating in low wind speed regions, the SG6043 airfoil profile is the most suitable as it showed a good aerodynamic performance at low wind speed.